In the construction field, precise estimation of elevation is of critical importance. For example, when grading a construction site, the construction crew must know the elevation of the equipment, in order to ensure that the site conforms to the plan designed by the engineers and architects. These elevations may be absolute, or they may be relative to some reference point on the site.
Global positioning system (“GPS”) receivers (or other global navigation satellite system (“GNSS”) equipment) are sometimes used to estimate elevations. Limitations in this technology have traditionally prevented the use of such systems for precise elevation measurements, however. Although recent enhancements in the technology have improved such systems, they often still cannot attain the precision required for many tasks.
Laser technology is often used for elevation estimation as well. Such systems typically will transmit a beam from a laser emitter to a laser detector. Based on the known elevation of the emitter, the slope of the beam (from the horizontal), and the distance between the emitter and the detector, the elevation of the detector (and, correspondingly, any equipment to which the detector is attached) can be calculated. Such systems typically can offer enhanced precision over GPS-based systems. However, existing laser-based systems have problems dealing with any significant changes in the elevation of the detector, which will cause the emitted beam to miss the detector. Some systems implement a fan beam (which effectively emits the beam over a broader area than a rotating spot beam), allowing for greater flexibility in the elevation of the detector relative to the emitter. Such systems are not without problems either, however. In particular, the use of a fan beam typically requires the use of more complex emitters and also requires significant calculation to determine elevation based on the received beam (since the emitted beam covers a broader vertical spectrum at the point of reception). A fan beam design also emits a larger fan beam, increasing power requirements and/or reducing range of the possible detection.
A potential solution to these issues is the use of a rotating spot beam in an emitter that is conditioned to calculate the proper slope of the beam. One such solution provides the emitter with GPS coordinates of the detector and forces the emitter to calculate the proper slope of the beam based on the location of the detector. This potential solution, however, requires significant computing power in the emitter (raising costs) and often prevents effective use of the emitter with multiple mobile stations (each of which is in a different location and each of which has its own detector) and reduces the ability to use other information from the mobile station, for example expected terrain that the detector is about to move over. This method also can have significant radio transmission overhead as the emitter needs to be in contact with the mobile station often Hence, this solution often will require multiple, expensive emitters to accommodate the number of detectors at use on a typical site.
A simpler solution would be to implement larger detectors, which would allow for greater variation in detector elevation before the detector ceases to receive the beam. Such detectors, however, require a relatively large number of sensors, which are quite expensive. Accordingly, the cost of implementing larger detectors can quickly become prohibitive.
Accordingly, there is a need in the art for tools and techniques that accurately and precisely estimate elevations while addressing these types of issues.